P1

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• Created by: robyn16
• Created on: 24-01-14 16:50
What is heat measured in?
Energy
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How does heat travel around?
Heat travels from hot objects to cooler surroundings, E.g. Warm radiator to the cold air in the room.
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What is specific heat capacity?
the measure of how much energy a substance can store
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What is the equation for specific heat capacity?
Energy = Mass X Specific Heat Capacity X Temperature Chnage
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When you heat a liquid, what happens to the particles?
the particles move faster
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What are the flat points on a graph of melting or boiling?
because the energy used is used for breaking intermolecular bonds rather than raising the temperature
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What is specific latent heat?
the amount of energy needed to change state/ needed to melt 1kg of material without changing it's temperature
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How do you break intermolecular bonds?
put IN energy
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What is the equation for specific latent heat?
Energy: Mass X Specific Latent Heat.
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What the white, yellow and blue colours on the thermograms represent?
white- hottest parts of the image yellows- warm parts of the image blues- coldest part fo the image
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By infra red waves
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What does conduction mainly occur in? give an example
Conduction occurs in solids, for example metal
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Give the definition of conduction?
CONDUCTION OF HEAT IS WHERE VIBRATING PARTICLES PASS ON EXTRA KINETIC ENERGY TO NEIGHBOURING PARTICLES.
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Name 3 good conductors of conduction.
Copper, Steel, Iron, Aluminium, Titanium
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What does convection mostly occur in?
Liquids and gases
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Give the definition of convection.
CONVECTION OCCURS WHEN THE MORE ENERGETIC PARTICLES MOVE FROM THE HOTTER REGION TO THE COOLER REGION- AND TAKE THERE HEAT ENERGY WITH THEM.
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What relies on convection and why?
radiators, to make the air circulate the room
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Why doesn't convection occur in solids?
because the particles cannot move around
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Where does heat radiation usually occur?
air, glass or water
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What colour is a good absorber?
matt black
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What isn't a good absorber?
light-coloured or shiny or smooth objects
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Why is hear radiation important in cooking?
The heat radiated by the grill is absorbed by the surface particles in the food. Use shiny foil in to reflect the waves back onto the food. Microwaves penetrate the surface of the food where all the water or fat molecules, increasing the kinetic ener
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What is payback time?
It costs money to install insulation but it saves money in the long run as your bills will be lower. Eventually the money saved on energy bills will equal the initial cost
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Name 4 ways to save energy?
loft instulation, hot water tank jacket, doubke glazing,thick curtains,draught proofing, cavity walls and insulation
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What is the main thing that is reduced in saving energy?
convection
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What is efficiency?
How efficient a machine is, the less energy wasted the more efficiet the machine is said to be
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How is energy usually lost in efficieny?
usually as heat
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What number does the efficiency ALWAYS have to be between?
0-1
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What is the equation of efficiency?
Efficiency=useful energy output DIVIDED BY total energy output (X 100%)
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Describe a sankey diagram.
The Thickness of the Arrow represents the Amount of Energy. The thicker the arrow the more energy it represents.
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What are the three main things a wave has?
amplitude, wave length and frequency?
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Give the definitions of the amplitude, wave length and frequency.
Amplitude- displacement from the rest position to the crest ( middle to top) wave length- from crest to crest frequency- number of full cycles passing a certain point per second
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what is the equation for wave speed?
speed= frequency X wavelength
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What 3 things can waves be done to them?
Reflected, Refracted and Diffracted
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What is reflection of light?
is what allows us to see objects, when light reflects off an uneven surface it reflects off at different agnels.
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What is the law of reflection?
Angle of INCIDENCE = Angle of REFLECTION
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What is the rule of when the incident light ray is reflected?
The reflection has to be the same angle off the normal line
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What is total internal relfection?
when the angle of incidence is bigger than the angle of reflection the light will then bounce back into the material
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What is diffraction?
the waves spread out at the edges when they pass through a gap or pass an object
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The narrower the gap the...
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What is refraction?
changes the speed of a wave, when the waves go from a less dense to a dense material AT AN ANGLE
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What are the 7 types of electromagnetic waves?
Radio waves, microwaves, infra read, visible light, ultra violet, x rays, gamma rays
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What ray has the highest frequency?
gamma rays, more dangerous
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What ray has the lowest frequency?
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Are the rays at each end absorbed or pass through a material?
Pass through material
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What is ionisation?
is where an atom otr molecules either looses or gains electrons
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What waves are used for communication?
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Name 3 advantages of different signals.
signals travel fast, carries lots of information and fast, sent through optical fibres are very secure
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difficult to repair, can have bad signal strength
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How is the morse code shown?
each letter and number is represented by a sequence of dots and dashes which are pulses of light
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What are optical fibres?
they carry data over long distances as pulses of light or infra red radiation
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How do optical fibres work?
waves bounce off the sides of a narrow core, it enters the fibre so that it hits the boundry between the core and the outer cladding at an angle greater than the critical angle. This continues until it gets to the other end.
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What are the advantages of light?
very quick, travels through a vacuum, lots of signals can be transmitted down ONE single fibre at the same time, little interference
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What type of light do lasers produce?
narrow, intense beams or MONOCHROMATIC light
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How is light monochromatic?
all the waves are the same frequenc which means that its all one single, pure colour
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Why do CD's have shallow lands cut into them?
the laser beam is relfected from the land and pit a bit differently. These can be picked up by light which is reflected and changed into electrical signal. The amplifier convert the electrical signal into sound
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Name 4 ways that infra red is used?
cooking, remote controls, transmit betwene mobile phones, security systems
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What can infrared be used for?
to monitor temperature like humans
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How is infra red given out?
by hot objects, the hotter the object the more infra red is given out
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Give another way infrared is detected?
night vision equipment, it turns into an electrical signal which is displayed on a screen. The hotter the object the brighter it appears, police use this to track down run aways
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How do infrared signals control electrical equipment?
the puleses ast as a digital code. The device then detects and decodes the pattern
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What is a disadvantage of infrared signals?
you need to be close to the device as infrared beams are small and low powered (weak)
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Why are radio waves/microwaves good at transmitting information over long distances rather than infra red or gamma rays?
because they don't get absorbed by the earths atmosphere
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Wat are radiowaves mainly used for?
communication
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Why do long-wave radio get transmitted to around the world?
because they bend/diffract around the curved surface
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Radio waves are used for Tv's. They are short waves. How do you get reception?
you have to be un direct slight of the transmitter- signal doesn't bend around hills or travel through buildings
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Why do longer waves encounter alot of diffraction?
because they a larger compared to the object they are passing, this means theyare able to bend round corners
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Why do some areas have trouble recieving signals?
becasue the recievers are not in line with each other and it will be poorer than normal
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What is the ionosphere?
UV radiation from the sun create layers of ionised atoms. These electically charged layers are called the ionosphere
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What sort of waves are reflected back into the ionosophere?
short wave lengths-
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Why so analogue signlas often suffer interference?
because they have similar waves covering a similar area
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How does Digital Audio Broadcasting (DAB) work differently to analogue?
lots of signals are compressed. These are transmitted across relatively small frequency and separated by recievers
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less interference, more stations
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limited number of DAB transmitters, sound quality isn't as good
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What are microwaves used for?
satallite communication
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How are the signals transmitted for tv's?
it is transmitted into space where it is picked up by the satalite dish. This then transmits the signal back to earth where it is recieved by a different satallite dish
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How do microwaves transmit signals to help mobile phones?
they go from your phone to the nearest transmitter, these pass signals between each other then back to your mobile.
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What is the disadvantages of having short wave lengths for mobile phones?
they dont diffract much, they are affected by the curvature of the earth, blocked more by large obstcles
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Why are mobile masts so dangerous?
if microwaves are absorbed by water molecules in living tissure they can be killed, could damage health,
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What is the conflicting evidence of mobile masts?
prolonged exposure throguh livign close to the masts or using your phone all the time.
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Why do we use different recievers?
to pick up different EM waves used for communication
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What wave needs the biggest reciever?
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Why do radiowaves need the biggest reciever?
because of diffraction. when a wave entres a reciever though a gap, some detail is lost
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What do telescopes do?
helps to see distant objects, they collect different EM waves
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Why are optical microscopes dffraction limited?
becasue they are so small, you usually have to look at them in small samples like in labs. The small size makes it hard to get a good resolution
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Why is information converted to electrical signals?
to produce sounds and pictures, these are then sent down telphone wires
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Does analouge vary or simply be on or off?
vary due to the amplitudr and frequency of the waves
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What two values can digital take?
on/off OR 1/0
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What are the advantages that digital has over analouge?
The noise can be easily removed, can trasnmit several signals at the same time
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Disadvantages of both, digital and analogue.
Signals weaken as they travel, pick up interference and noise
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What is 'Multiplexing'?
this happens in phone wires. When your on the phone, your voice is converted into a digital signal anf trasnmitted at very small time intervals. In between your voice, thousands of other peoples voices can be slotted in.
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skin cancer
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Why does ultra violet radiation cause skin cancer?
it damages the DNA in your skin cells
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Why does darker skin have more protection against UV rays?
it absorbs more UV radiation which prevents the radiation reaching the more vunerable tissues in the body.
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How does the Ozone layer protect us from the UV radiation?
the ozone layer absorbs some of the UV rays from the sun so it reduces the amount that reaches the earth surface.
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Why had the ozone layer got thinner recently?
CFC's react with the ozone molecules and break them up, this allows more UV rays to get through to the earths surface.
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What are the two types of seismic waves?
P-waves; longitudinal S-waves: transverse
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What do P waves travel through?
solids and liquids and travel FASTER
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What do S waves pass through?
only pass through Solids
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Why do p waves change direction?
it shows theres a sudden change in properties
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Other cards in this set

Card 2

Front

How does heat travel around?

Back

Heat travels from hot objects to cooler surroundings, E.g. Warm radiator to the cold air in the room.

Card 3

Front

What is specific heat capacity?

Card 4

Front

What is the equation for specific heat capacity?

Card 5

Front

When you heat a liquid, what happens to the particles?